Jump-Start Your Metabolism

And Get Your Body to Work for You

By Ronald Klatz, MD and Robert Goldman, MD

On a cellular scale, metabolism is the breakdown of fats, proteins or carbohydrates and how our cells, organs, and tissues process these fuels. On a broader scale, metabolism is not merely the process of burning up the calories we consume from food, but rather how the various nutrients from that food help us maintain a healthy body.

Metabolism slows with age, thereby contributing to weight gain in our older years. After age 45, the average individual loses around 10 percent of their muscle mass per decade. This equates to losing about one-third to one-half a pound of muscle each year and also gaining that much in body fat.

A comprehensive study funded by the Agricultural Research Service suggests metabolism may slow with age because of a gradual loss of body cells, especially high-energy-consuming muscle cells. As a result, people burn fewer calories while at rest when they're older, which often leads to weight gain over time.

Some scientists have suggested that changes in hormones, immune function or other factors may depress resting metabolism with aging. This study, a statistical analysis conducted by researchers at the Human Nutrition Research Center on Aging at Tufts University in Boston, showed a direct association between metabolic rate and cell mass, also known as lean- or fat-free mass. This means that older people may actually be able to regain some of the resting metabolic rate they had when they were younger by doing regular muscle-building exercises. Increasing muscle mass would help seniors ward off obesity, according to the researchers.

Exercise isn't the only way to boost metabolism, of course; research also suggests proper nutrition can play a key role in getting your body to work for you. People who are physically fit, eat a healthy, balanced diet, and take nutritional supplements can measure out to be up to 20 years biologically younger than their chronological age. Let's take a look at what the science is saying about ways to jump-start your metabolism and keep it working for you for a lifetime.